Infrared rays in the non-visual range having a long wave-length such as far infrared rays have an excellent thermal effect such as high absorption of heat rays into a human body, promotion of circulation of blood and recovery of fatigue of muscles. In the prior art, there has been used a mattress for radiating far infrared rays as shown in FIG. 6. The prior mattress comprises a relatively solid plate-like support A, a sheet-like heater B provided on the support a from the top to the bottom of the mattress and having electric resistance material of carbon in a rectagular form covered with an insulated sheet of vinyl, a thin cushion body C of chemical fiber or foamed polyurethane in the form of a plate provided on the heater B and an outer cover D covering a laminate of the support A, the heater B and the cushion body C.
However, since such a prior mattress radiating far infared rays has the sheet-like heater including the cover of vinyl, there is no ventilation of air and humidity and/or sweat is difficult to remove from the mattress. This causes the user to feel uncomfortable. Also after the mattress is used for a long time, the resilience of the cushion body decreases and humidity and/or sweat is more difficult to remove from the mattress. Thus, moisture remains in the mattress, which causes mildew and/or a bad odor to occur in the mattress. Furthermore, since the prior mattress is relatively thin and solid, the user feels and produces only thermal effects. In addition thereto, since the mattress is required to have large dimensions sufficient for covering the human body from the feet to the breast thereof, high electric power is required to be consumed.